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    SubjectRe: About 4k kernel stack size....
    On Tue, Dec 20, 2005 at 09:37:28AM -0500, Mike Snitzer wrote:
    > On 12/20/05, Adrian Bunk <> wrote:
    > > On Mon, Dec 19, 2005 at 09:52:53PM -0500, Mark Lord wrote:
    > > >...
    > > > The mainline code paths are undoubtedly fine with 4K stacks.
    > > > It's the *error paths* that are most likely to go deeper on the stack,
    > > > and those are rarely exercised by anyone. And those are the paths
    > > > that we *really* need to be reliable.
    > >
    > > "most likely" is a strong sentence, especially considering that the
    > > automatic analysis of all possible call chains can and has already
    > > identified several such problems (which have now been fixed many months
    > > ago).
    > >
    > > We might not getting 100% security against stack overflows, but that's
    > > not fundamentally different from the current situation with 6 kB stacks.
    > Given this last statement, why is it that Matt Mackall's suggestion in
    > the "Light-weight dynamically extended stacks" thread didn't get any
    > _real_ discussion from the big 4K stack advocates? For all intents
    > and purposes, Matt was dismissed with the same Bunk: "Ever since
    > neilb's patch there are 0 bugs.. blah blah". 4K, 8K (aka "6 kB")
    > aside; having more stack safety in the Linux kernel is a "good thing"
    > no? Aren't dynamic stacks a viable means to imposing 4K (but doing so
    > with real safety)?

    Besides the fact that I still don't think it's requred, Matt's
    suggestion would work only randomly for functions using more than 1 kB

    But discussing hypothetical patches is silly - code talks.

    If someone sends a patch implementing Mark's suggestion and it gets
    measured that this patch doesn't impose a performance penalty we'd
    have a basis for a real discussion.

    > Mike



    "Is there not promise of rain?" Ling Tan asked suddenly out
    of the darkness. There had been need of rain for many days.
    "Only a promise," Lao Er said.
    Pearl S. Buck - Dragon Seed

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